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Cant deficiency

 Cant deficiency is the difference between actual cant provided and equilibrium cant necessary for the maximum permissible speed on a curve

Cant deficiency should be as low as possible and is limited due to the following reasons

1. Higher discomfort to the passenger due to Higher cant and deficiency.

2.higher cant deficiency result in higher unbalanced centrifugal force and hence extra pressure and lateral trust on the outer rail requiring strong track and more fastening for stability

3. Side wear and creep of outer rail of the track are more due to the higher cant deficiency

Maximum value of cant deficiency as prescribed on Indian railway are given below



Negative cant

On curve branch line meet the main line at a certain place. The outer rail of the main line on the curve with the inner rail of the branch line. as the superelevation is provided on the main line the outer rail of the mainline is at a higher level than the inner. the inner rail of the branch line will have to be kept at higher level than the outer rail. For superelevation at the curve outer rail remains at higher level than the inner .but whereas outer rail in branch line is at a lower level than inner rail the superelvation provided on branch line is negative such type of superelevation is known as negative superelevation or negative cant. In figure 8.5 the line QS is at a higher level than line PT. In branch line PU should be at higher level than QV but ice point p is lower than q the line QV becomes at higher level than PU




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